Carburetor .

TM 55-4920-405-13&P

Insert the end of a small screwdriver

(i)

( b ) Zenith Carburetor. Repair this car-

into the coils of rocker arm spring

buretor as follows:

(12), and remove the spring.

Disassemble the carburetor.

(j) Hold mounting bracket (15) in your

(See figure 4-13.)

left hand, with the rocker arm turned

toward your body. Put your left hand

Clean all parts thoroughly. Blow

thumb nail on the end of link (10).

out all passages with low-pres-

sure air. Do not use a drill or

With the heel of your right hand on

diaphragm (1), compress diaphragm

wire to clean out passages.

spring (11) and, at the same time,

Inspect float assembly (36). Re-

pull toward your body. Unhook link

place it if it is loaded with gaso-

line. if it is damaged. or if the

(10) from the end of diaphragm (1),

float axle bearing is worn. In-

and remove the diaphragm.

(k) Drive out rocker arm pin (13). Use

spect the float lever for wear at

the point of contact with fuel valve

a punch and drive it from the small

end.

needle (31). Replace the float

assembly if wear is excessive.

(l) Clean mounting bracket (15) with

kerosene or diesel fuel.

Replace float axle (35) if its bear-

(m) Assemble new link (10), bushing (9),

ing surface is worn.

and rocker arm (14). Install these

Replace fuel valve needle and fuel

parts in mounting bracket (15), using

valve seat (31) as a unit if either

of these parts is worn.

pin (13). Stake pin (13) to mounting

bracket (15) to hold the pin in place.

Inspect the tapered end of idle

(n) Place new diaphragm spring (11) into

adjusting needle (17). Make sure

that it is smooth and free of

mounting bracket (15). Use a new

grooves; otherwise, replace the

diaphragm (1), and install the dia-

idle adjusting needle.

phragm by reversing the procedure of

step (j).

Replace all gaskets. throttle shaft

seal (15), and retainer (14).

(0) Assemble new rocker arm spring (12).

(p) Mount the mounting bracket and as-

Replace all other parts that show

signs of wear or damage.

sembled parts on the fuel pump

Reassemble the carburetor.

adapter on the engine. Use a new

flange gasket (17).

Note the following special instruc-

tions during reassembly:

(q) Crank the engine to a position where

diaphragm (1) is lying fiat on mount-

To install float assembly (36),

ing bracket (15). Place fuel head (16)

install fuel valve needle in

with its attached parts in position so

seat (31). Then, install float

that the groove marks you made in

assembly (36) and float axle

step (a) are in line. Insert screws (3)

(35).

and turn them in about three turns.

(r) Crank the engine to a position where

NOTE

diaphragm (1) is pulled down to its

lowest position in mounting bracket

Insert the tapered end of float axle (35) in-

(15). Tighten screws (3).

to the float bracket on the side opposite the

slot, and push it through to the other side.

(2)

C a r b u r e t o r . You will find either of two

Press float axle (35) into the slotted side

types of carburetors on your engine.

until the float axle is centered in the float

Identify your carburetor, and repair it by

bracket.

following the correct procedure below.

After installing float assem-

( a ) Marvel-Schebler Carburetor. Repair

bly (36), invert body (26).

this as follows:

Check to see that the float

body of float assembly (36) is

Disassemble the carburetor.

centered at right angles to the

(See figure 4-12.)

machined surface. Using a

Clean all parts thoroughly. Blow

depth gage, measure the

out all passages with low-pressure

distance from the machined

air. Do not use a drill or wire to

surface of body (26). with n o

clean out passages.

gasket, to the top side of the

Inspect the tapered end of idle

float body at the highest point.

adjusting needle (22). Make sure

This distance must be 31/32

it is smooth and free of grooves;

1/32 inch. If the nleasure-

otherwise, replace it.

ment is off by more than 1/16

Replace all gaskets and packings.

inch, replace float assembly

Replace all other parts that show

(36). If it is off by 1/16 inch

signs of wear or damage.

or less, bend the lever arm

Reassemble the carburetor.

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